Programmable thermostats for furnaces, boilers, heatpumps, air-conditioning systems or combinations thereof are well known in the art, to reduce heating or cooling demand to buildings during times when they are unoccupied or when inhabitants thereof are in bed and thus can remain comfortable with a lower ambient temperature. This can result in considerable energy savings with little effect on the comfort of users. Such programmable thermostats typically permit programming different desired temperatures for selectable time periods.
Similarly, water heaters can benefit from programmable control. There are programmable thermostats for electric water heaters known in the art. Systems incorporating a programmable thermostat with an electric water heater have the disadvantage of adding complexity to water heater products and require increased inventory for sellers. As well, because electric water heaters have a fairly long recovery time, for such thermostatically controlled systems to function well, they require thermostats with additional learning features to monitor the recovery time and activate the water heater in advance of the programmed time. Programming a water heater thermostat independently of a furnace or air conditioner thermostat imposes extra effort on users.
It is an object of the present invention to provide an easy-to-use programmable thermostat adapted to control a heating and/or cooling system, including a furnace, boiler, heatpump, air-conditioning system or any combination thereof in conjunction with a fossil-fueled water heater such as natural gas or propane powered water heater.